Regenerative heat exchanger

ABSTRACT

A regenerative heat exchanger comprising at least one pistonlike matrix arranged to be reciprocated in a cylinder or respective cylinders, the or each cylinder having a first pair of inlet and outlet ports with which the respective matrix cooperates when it occupies a first position in the cylinder, and a second pair of inlet and outlet ports with which the matrix cooperates when it occupies a second position in the cylinder, whereby relatively hot and cold fluid streams which pass through the respective pairs of ports will pass alternately through the matrix as the matrix alternately occupies its first and second positions.

United States Patent 1 Penny 1 June 24, 1975 I REGENERATIVE HEAT EXCHANGER [22] Filed: Nov. 12, 1973 [21] Appl. No.: 414,723

[30] Foreign Application Priority Data Nov. 28, 1972 United Kingdom 54896/72 [52] US. Cl 165/6; 165/10 {51] Int. Cl. F28d 17/00 [58] Field of Search 165/6, 10

[56] References Cited UNITED STATES PATENTS 3,404,965 10/1968 Shiller 165/10 X FOREIGN PATENTS OR APPLICATIONS 760,803 11/1956 United Kingdom 165/6 11/1961 Canada 165/10 6/1961 Germany 165/6 Primary E.\'aminr-Albert W. Davis, Jr. Attorney, Agent, or Firm-Gifford, Chandler & Sheridan [57] ABSTRACT A regenerative heat exchanger comprising at least one piston-like matrix arranged to be reciprocated in a cylinder or respective cylinders, the or each cylinder having a first pair of inlet and outlet ports with which the respective matrix co-operates when it occupies a first position in the cylinder, and a second pair of inlet and outlet ports with which the matrix co-operates when it occupies a second position in the cylinder, whereby relatively hot and cold fluid streams which pass through the respective pairs of ports will pass alternately through the matrix as the matrix alternately occupies its first and second positions.

6 Claims, 4 Drawing Figures Ijt REGENERATIVE HEAT EXCHANGER BACKGROUND OF THE INVENTION The invention relates to a regenerative heat exchanger and is particularly, but not exclusively, concerned with a regenerative heat exchanger for a gas turbine engine.

SUMMARY OF THE INVENTION According to the invention, a regenerative heat exchanger comprises a piston-like matrix reciprocatable in a cylinder provided in a housing, the cylinder having a first pair of inlet and outlet ports with which the matrix co-operates when it occupies a first position in the cylinder, and a second pair of inlet and outlet ports with which the matrix co-operates when it occupies a second position in the cylinder, whereby relatively hot and cold fluid streams which pass through the respective pairs of ports will pass alternately through the matrix as the matrix alternately occupies its first and second positions, and means for reciprocating the matrix in the cylinder.

The matrix is preferably arranged to close the first pair of inlet and outlet ports before opening the second pair of inlet and outlet ports and vice versa.

A plurality of cylinders may be provided in the housing, each cylinder containing an associated matrix. In such a case, the cylinders may be arranged with their longitudinal axes parallel with each other and circumferentially spaced apart around an imaginary pitch circle in the housing. Where the cylinders are so arranged, the matrices may conveniently be moved in their associated cylinders by a swash-plate or equivalent means whereby the matrices will be moved in cyclic order. Alternatively, the cylinders may be carried by a part of the housing rotatable about the axis of said imaginary pitch circle and the matrices operated in cyclic order by their successive engagement with a stationary camplate as the housing is rotated about said axis.

The or each matrix may be in the form of a block of a porous ceramic or ceramic-like material such as silicon nitride. Alternatively the or each matrix may comprise a hollow piston casing filled with a porous or foam-like, heatresistant material and having ports cooperable with the aforesaid inlet and outlet ports in the associated cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS A regenerative heat exchanger in accordance with the invention will now be described by way of example with reference to the accompanying drawings, in which:

FIG. I is a cross-section through a housing defining a cylinder and illustrating a matrix in a first axial position in the cylinder;

FIG. 2 is a view similar to FIG. 1 showing the matrix in a second axial position in the cylinder;

FIG. 3 is an axial cross-section, to a smaller scale, through a housing including a plurality of cylinders each corresponding to the cylinder shown in FIGS. 1 and 2 and showing the matrix ofone cylinder in an axial position in its cylinder corresponding to FIG. 1 and the matrix of another cylinder in an axial position in its cylinder corresponding to FIG. 2, and

FIG. 4 is a cross-section, to the same scale as FIGS. I and 2, on the line IV-IV in FIG. 3 and showing the matrices in successive axial positions in their cylinders.

DETAILED DESCRIPTION OF THE INVENTION With reference firstly to FIG. 1, a housing 1 defines a cylinder 2 in which a matrix 3 is axially slidable. The cylinder has inlet and outlet ports 4, 5 for cool gases. The inlet port 4 may be arranged to receive cool gases from a compressor of a gas turbine engine (not shown). The ports 4, 5 are at diametrically opposite positions in the cylinder 2. The cylinder 2 is also provided with inlet and outlet ports 6, 7 respectively for hot gases. The port 6 may receive hot gases from a turbine of the gas turbine engine. The ports 6, 7 are at diametrically opposite positions in the cylinder 2.

The matrix 3 comprises a piston-like tubular metal casing 8 having closed ends and which is sealingly slidable within the cylinder 2. The casing 8 is formed with diametrically opposite ports 9, .10 which may be optionally aligned with the ports 4, 5, as shown in FIG. I, or with the ports 6, 7 respectively as shown in FIG. 2 according to the axial position of the matrix 3 in the cylinder 2. The casing 8 is filled with a porous or foamlike heat resistant material 11 e.g., silicon nitride.

In use, and with the matrix 3 occupying the position shown in FIG. 2, hot gases are directed into the matrix 3 through the aligned ports 6, 9 to heat the heatresistant material 11 before passing through the aligned ports 10, 7 and thence, for example, to atmosphere. The matrix 3 is then moved axially to the right into the position shown in FIG. 1 and closes the ports 6, 7 before the ports 4, 5 become aligned with the ports 9, 10 in the casing 8 of the matrix 3. Cool gases, for example air from a compressor of a gas turbine engine, then enter the previously heated material 11 of the matrix 3 through the aligned ports 4, 9, the air being heated by the material 11 before passing through the aligned ports 10, 5 and thence, for example, to a combustion chamber of the gas turbine engine. The matrix 3 is then moved axially to the left into the position shown in FIG. 2, the matrix 3 closing the ports 4, 5 before the ports 6, 9 and 7, l0 become aligned. The cycle is then repeated.

The matrix 3 may be reciprocated in the cylinder by means of a piston rod 12 which may be engaged by a cam (not shown) operated, for example, by a rotary shaft of the gas turbine engine.

If desired, a plurality of cylinders of the kind shown in FIGS. 1 and 2 may be provided in a housing of annular or cylindrical shape and arranged with their longitudinal axes parallel and spaced apart around a pitch circle X (see FIG. 4). The arrangement is shown in FIGS. 3 and 4 in which like parts also appearing in FIGS. 1 and 2 are indicated by the same reference numbers.

In FIGS. 3 and 4 the ports 4, 5 of a cylinder 2 at a position A are shown in alignment with the ports 9, 10 of the casing 8 of the matrix 3 as in FIG. 1. Air under pressure from, for example, a compressor of a gas turbine engine enters a duct 13 which communicates with the ports 4 of all the cylinders. After passing through the material 11 of the matrix 3 and the ports 10 and 5, the air enters a chamber 14 defined between the cylinders 2 and the housing 1. The chamber 14 directs heated air under pressure from the matrix 3 to, for example, a combustion chamber of the gas turbine engine.

Meanwhile, the ports 6, 7 of a cylinder 2 at a position B are in alignment with ports 9, 10 of the casing 8 of the matrix 3 as shown in FIG. 2. Hot gases under pressure from, for example, a turbine of the gas turbine engine enter a further duct which communicates with the ports 6 and after passing through the material 11 of the matrix 3 and the ports 10, 7 are discharged, for example, to atmosphere.

Although the air and gas flows through the cylinders are in the same radial directions, the flows may alternatively be in theopposite radial directions, that is equivalent to counter-flow. I

Each matrix carries a piston rod 12, as in FIGS. 1 and 2, of which the outer end engages a ball bearing 17 carried by a-shoe l8 engaging a swash-plate 19, or rotatable cam, arranged for rotation by a shaft (see FIG. 3). By rotating the shaft 20, the swash-plate 19 will effect reciprocation of the matrices 3 in their respective cylinders 2 in a cyclic order between the extreme positions indicated by A and B. The matrices are urged to the left in FIG. 3 by helical springs 21.

Alternatively, the housing 1 carrying the cylinders 2 maybe rotatable about-a longitudinal axis parallel with the axes of the cylinders and passing through the center of the pitch circle, and theswash-plate I9 is replaced by a stationary cam plate having an inclined face causing the matrices to be reciprocated in cyclic order. The stroke of the matrices 3 may be adjusted by altering the angle of. the swash-plate 19 or cam-plate. Instead of using a swash-plate 19, a plurality of synchronised cams may be used.

Although the cylinders 2 have been shown arranged on pitch circles in FIGS. 3 and 4, they may be arranged in any other suitable form. For example, the cylinder axes may be radially spaced from each other -or arranged on two or more concentric pitch circles.

Instead of each matrix comprising the casing 8 and porous or foam-likematerial 11, each matrix may be a cylindrical block ofa porous ceramic or ceramic-like material such as silicon nitride.

Although the matrices have been shown as true cylinders, they may be hollow cylinders (i.e. annular) or .they may be curved in the longitudinal direction. In the latter case the cylinders would be similarly curved longitudinally.

Although the matrices have been shown as cylinders reciprocatable in the longitudinal direction, the pistons may be movable between the two operative positions by angular or helical oscillation.

What I claim as my invention and desire to secure by Letters patent of the United States is:

l. A regenerative heat exchanger comprising a housing, a plurality of cylinders contained in the housing 4 and arranged with their longitudinal axes parallel with each other and circumferentially spaced apart around an imaginary pitch circle in the housing, a piston-like matrix contained in each cylinder and reciproeatable therein. each cylinder having a first pair of inlet and outlet ports with which the matrix therein co-operates when it occupies a first position in the cylinder, and a second pair of inlet and outlet ports with which the matrix therein co-operates when it occupies a second position in the cylinder, whereby relatively hot and cold fluid streams passed through the respective pairs of ports will'pass alternately through each matrix as each matrix alternately occupies its first and second positions, reciprocating means for reciprocating the matrix in each cylinder such that sequentially one matrix is open to the relatively hot fluid and one matrix is open to the relatively cold fluid, and means for effecting relative rotation between said reciprocating means and said housing, whereby the matrices are reciprocated in their respective cylinders in cyclic order during said relative rotation.

2. A heat exchanger as claimed in claim 1 in which the matrix is arranged to close the first pair of inlet and outlet ports before opening the second pair of inlet and outlet ports and vice versa.

3. A heat exchanger as claimed in claim '1 in which-- the reciprocating means comprises a swash-plate .rotatable relatively to the housing by which the matrices are arranged to be moved in theirrespective cylinders in 6. A heat exchanger as claimed in claim 1 in which each matrix is in the form of a hollow piston casing and a mass of porous, heat-resistant material within said piston casing, the latter having ports co-operable with the aforesaid inlet and outlet ports in the associated cylinder. 

1. A regenerative heat exchanger comprising a housing, a plurality of cylinders contained in the housing and arranged with their longitudinal axes parallel with each other and circumferentially spaced apart around an imaginary pitch circle in the housing, a piston-like matrix contained in each cylinder and reciprocatable therein, each cylinder having a first pair of inlet and outlet ports with which the matrix therein co-operates when it occupies a first position in the cylinder, and a second pair of inlet and outlet ports with which the matrix therein cooperates when it occupies a second position in the cylinder, whereby relatively hot and cold fluid streams passed through the respective pairs of ports will pass alternately through each matrix as each matrix alternately occupies its first and second positions, reciprocating means for reciprocating the matrix in each cylinder such that sequentially one matrix is open to the relatively hot fluid and one matrix is open to the relatively cold fluid, and means for effecting relative rotation between said reciprocating means and said housing, whereby the matrices are reciprocated in their respective cylinders in cyclic order during said relative rotation.
 2. A heat exchanger as claimed in claim 1 in which the matrix is arranged to close the first pair of inlet and outlet ports before opening the second pair of inlet and outlet ports and vice versa.
 3. A heat exchanger as claimed in claim 1 in which the reciprocating means comprises a swash-plate rotatable relatively to the housing by which the matrices are arranged to be moved in their respective cylinders in cyclic order.
 4. A heat exchanger as claimed in claim 1 in which the reciprocating means comprises an inclined cam-plate against which the matrices engage and spring means for holDing the matrices against said cam-plate, and the means for effecting said relative rotation comprises means for rotating the housing relatively to said cam-plate, whereby the matrices are arranged to be moved in their respective cylinders in cyclic order.
 5. A heat exchanger as claimed in claim 1 in which each matrix is in the form of a block of a porous ceramic material.
 6. A heat exchanger as claimed in claim 1 in which each matrix is in the form of a hollow piston casing and a mass of porous, heat-resistant material within said piston casing, the latter having ports co-operable with the aforesaid inlet and outlet ports in the associated cylinder. 